The present invention relates generally to lug nut and wheel lug covers. More particularly, this invention relates to tamper resistant indicators of unauthorized lug nut removal.
This invention is an improvement upon the invention shown in U.S. Pat. No. 4,521,146, assigned to the same assignee as the present invention. The disclosure and specification of this prior patent are specifically incorporated herein by reference.
An object of the present invention is the provision of an improved lug nut cover.
Another object is to provide a lug nut cover having means for visually demonstrating successful and unsuccessful tampering attempts.
Still other object is the provision of an improved lug nut cover with restricted access to the retaining cap.
A further object is to provide a nut cover having means for positively preventing unthreading of the retaining cap.
These and other objects of the present invention are attained by the provision of a lug nut cover having a rigid plastic shroud which fits over a lug nut and threaded lug to restrict access to the lug nut. A retaining cap fits through a central aperture at one end of the shroud and is threaded onto the wheel lug. This cap secures the shield in place over the lug nut via a circumferential flange which seats on a shoulder or ledge in the central aperture. The cap includes a square socket opening extending from its exposed, outer face by which the cap can be threaded onto the lug with an appropriate tool. The inner wall of the shroud includes a plurality of thickened portions or legs. These legs serve to engage the planar sides of the lug t and prevent rotation of the shield relative to the lug nut. The shoulder of the central aperture and the cap flange include a cooperating pawl/ratchet arrangement which prevents reverse relative rotation between the cap and the lug once the cap is fully threaded into a predetermined locking position.
This invention is intended to provide an inexpensive, visual indication of whether or not a vehicle wheel has been removed since, once installed, the cover cannot be removed from the lug without breaking the cover. Both the shroud and the cap can be formed from breakable plastic materials and marked with distinctive colors or codes. The cap socket is not frangible to be broken off during installation but, rather, is left intact to restrict access to the cap and visually demonstrate tampering attempts. Thin walled portions of the socket are destructible in response to unauthorized reverse threading and thereby cause the socket walls to flex away from and out of engagement with a tool. Projecting portions of the socket walls restrict access to the cap face.
Once threaded down onto the shroud ledge, the cap cannot be unscrewed without destroying the non-reversible pawl/ratchet arrangement. Also, the lug nut is substantially covered and cannot be engaged by a tool and removed without destroying the shroud. The shroud legs and/or shroud material are formed so as to not be strong enough to permit the lug nut to be unthreaded by rotation of the shroud itself. Further, interlocking of the legs and the lug nut prevents the cap from being unthreaded by rotation of the shroud. Thus, the present invention provides tamper indications and restrictions in both the shroud and the cap.
These and other objects, advantages and novel features of the present invention will become readily apparent upon consideration of the following detailed description in conjunction with the drawings.